Fluid injector

Abstract

A Fluid injector has a housing ( 8 ) with a cavity and a coil ( 34 ) being arranged in the cavity. A valve needle ( 12 ) is arranged axially moveable along a predetermined axis (L) of the fluid injector. An armature ( 14 ) is arranged axially moveable along the predetermined axis (L) and is mechanically coupled to the valve needle ( 12 ). A reluctance element ( 42 ) is designed to have a permeability which is much smaller than the permeability of the housing ( 8 ) and is arranged such that a magnetic circuit with the housing ( 8 ) and the armature ( 14 ) also has the reluctance element ( 42 ).

1 . A fluid injector, comprising
 a housing with a cavity and a coil arranged in the cavity,   a valve needle being arranged axially moveable along a predetermined axis of the fluid injector,   an armature being arranged axially moveable along the predetermined axis and being mechanically coupled to the valve needle,   a reluctance element being designed to have a permeability which is much smaller than a permeability of the housing and being arranged such that a magnetic circuit comprising the housing and the armature also comprises the reluctance element.   
   
   
       2 . The fluid injector according to  claim 1 , wherein the permeability of the reluctance element is smaller than the permeability of the housing by a factor of between 30 and 45. 
   
   
       3 . The fluid injector according to  claim 1 , wherein the reluctance element is arranged and designed such that a magnetic flux of the magnetic circuit passes the reluctance element twice. 
   
   
       4 . The fluid injector according to  claim 1 , wherein the reluctance element is designed as a hollow cylinder and arranged such that in a direction perpendicular relative to the predetermined axis the reluctance element is arranged between the armature and the housing. 
   
   
       5 . The fluid injector according to  claim 1 , wherein the reluctance element having a relative permeability of below 100. 
   
   
       6 . The fluid injector according to  claim 1 , wherein the reluctance element is mechanically coupled to a valve body of the fluid injector. 
   
   
       7 . The fluid injector according to  claim 1 , wherein the fluid injector comprises a valve body being formed integrally with the reluctance element. 
   
   
       8 . The fluid injector according to  claim 6 , wherein the valve body has a permeability which is much smaller than the permeability of the housing. 
   
   
       9 . The fluid injector according to  claim 8 , wherein the permeability of the valve body is smaller than the permeability of the housing by a factor of between 30 and 
   
   
       10 . The fluid injector according to  claim 6 , wherein the valve body has a relative permeability of below 100. 
   
   
       11 . A method for providing a fluid injector, comprising the steps of:
 arranging a coil in a cavity of a housing,   arranging a valve needle axially moveable along a predetermined axis of the fluid injector,   arranging an armature axially moveable along the predetermined axis and mechanically coupling the armature to the valve needle,   arranging a reluctance element with a permeability which is much smaller than a permeability of the housing such that a magnetic circuit comprising the housing and the armature also comprises the reluctance element.   
   
   
       12 . The method according to  claim 11 , wherein the permeability of the reluctance element is smaller than the permeability of the housing by a factor of between 30 and 45. 
   
   
       13 . The method according to  claim 11 , comprising the step of arranging and designing the reluctance element such that a magnetic flux of the magnetic circuit passes the reluctance element twice. 
   
   
       14 . The method according to  claim 11 , comprising the steps of designing the reluctance element as a hollow cylinder and arranging the reluctance element such that in a direction perpendicular relative to the predetermined axis the reluctance element is arranged between the armature and the housing. 
   
   
       15 . The method according to  claim 11 , wherein the reluctance element having a relative permeability of below 100. 
   
   
       16 . The method according to  claim 11 , comprising the step of mechanically coupling the reluctance element to a valve body of the fluid injector. 
   
   
       17 . The method according to  claim 11 , wherein the fluid injector comprises a valve body being formed integrally with the reluctance element. 
   
   
       18 . The method according to  claim 16 , wherein the valve body has a permeability which is much smaller than the permeability of the housing. 
   
   
       19 . The method according to  claim 16 , wherein the valve body has a relative permeability of below 100. 
   
   
       20 . The method according to  claim 18 , wherein the permeability of the reluctance element is smaller than the permeability of the housing by a factor of between 30 and 45.